Telephone metering system



Jan. 14, 1941. H TPFER 2,228,375

TELEPHONE METERING SYSTEM Filed Oct. 20, 1937 INVENTQR. HERBERT TOPPER ATTORNEY.

Patented Jan. 14, 1941 PATENT `FFICE TELEPHONE `METERING SYSTEM Herbert Tpfer, Berlinassignor to Siemens Siemensstadt, Germany, & HalskeV Aktiengesellschaft, Wernerwerk, Siemensstadt, near Berlin, rGermany Application October 20, 1937, Serial No. 170,081

' In Germany October 22, 1936 11 Claims.

The invention relates to a circuit arrangement for inuencing meters arranged at subscribers stations and in particular for iniluencing such meters at the end of the call by metering impulses transmitted from an exchange over the subsubscribers line.

Since the use of meters at the subscribers stations is particularly important in cases where a station is also accessible to strangers who then have to recompense the station subscriber for the cost of the calls it is a necessary requirement that the person using the station should not be able to influence the metering operationby any kind of manipulation with the view to suppressing the influencing of the meter indicating the fee in or' der to obtain an advantage at the expense of the station subscriber.

Arrangements are already known which aim at inuencing the fee indicator without any possibility of interference on the part of the party using the station. Of these arrangements only one will be mentioned which consists in influencing the fee indicator whichis connected to earth at the subscribers station by alternating current impulses transmitted simultaneously over both the speaking leads of the subscribers line. With this arrangement it is not possible in normal cases for the party using the station either wholly or partially to prevent the fee indicator from being inuenced from the exchange for example by quickly taking up the receiver again after giving the clearing signal or by operating the dial switch, since with this arrangement the establishment of a loop has no influence on the metering process.

This known arrangement, however, does not insure that the metering impulses shall be transmitted without any possibility of interference on the part of the party using the station if the latter is in a position to apply earth potential to the casein private branch exchange systems,

earth impulses are transmitted over the speaking leads on operating the dial switch. In these cases the simultaneous operation over both leads would not give any satisfactory solution since with this arrangement the alternating current transmitted for metering would pass to the earth connected directly to the speaking line.

The present arrangement avoids these difficulties and insures an eflicient influencing of the fee indicator even in the event of earth being applied at the subscribers station, and this is realized in that a switching means which on the initiation of a call prepares for the disconnection of the sub- 55 scribers station maintains the complete disconone of the speaking leads or if, as for example is nection of the latter which takes place in dependence upon the giving of the clearing signal, until the end of the inuencing of the meter at the subscribers station.

The drawing represents one embodiment of the invention. The invention is here represented incorporated in a lprivate branch exchange system but it must be expressly mentioned that the invention is not limited to such systems.

HS is the operators position of a private branch exchange system. At the operators position is shown the alternating current phase relay W which is connected to the upper speaking lead over a resistance and serves for calling the operators position from the exchange. In addition there are shown two contacts to be operated by the exchange key AT and the dial switch contacts ns1' and 'risa the rst of which is operated impulsively on the transmission of numerical impulses while the latter is closed so long as the dial switch is off normal. MT represents diagrammatically the microphone and telephone of the operators position. GAT represents the fee indicator and the switching means required for its connection l and operation. AL represents the line to the exchange and AZ auxiliary exchange equipment comprising a metering relay ZR which applies alternating current to the upper speaking lead in synchronisrn with the metering impulse. SP represents the feeding bridge for the private branch exchange system and VW the preselector associated with the private branch exchange line.

When the receiver is taken up at the operators position for the purpose of setting up a public earth, choke-coil, Dr2, the closed Contact of the D exchange key AT, MT, AT, nsz', winding of relay A, contact 3h, the connecting line AL, contacts 'Ier and It, the winding of the calling relay R, battery and earth. The calling relay starts up the preselector in the known way (not indicated) for testing una free succeeding connecting device. In the above circuit relayv A in the fee indicator assembly GAT also energises and at contact 5a disconnects earth from the fee indicator GA and switches through the upper speaking lead at contact 2a independently of contact 3h. Through the closing of contact to. the following circuit is set up for relay H over the feeding bridge SP; earth, contact 6a, winding of relay H, choke-coil DTZ, lower speaking lead, choke-coil DTS, chokecoil D1' 4 in the feeding bridge, battery and earth.

Relay H energizes in this circuit and opens its contact 3h and thereby opens a point in the upper speaking lead which had previously been shunted by contact 2a.

When the preselector has found a free succeeding connecting device the seizing relay T energizes in the preselector in the known way and performs the known functions of bringing the switch to rest, guarding and switching through. Through the opening of contact lot the calling relay R and the battery connected to this relay are disconnected while at contact .lit the upper speaking lead is connected to the impulse receiving device in the succeeding device. The relay A in the fee indicator assembly GAT is held energized over this impulse receiving relay and battery.

The operator now transmits the numerical impulse trains required for the establishment of the call. After the dial switch has been drawn orinormal earth potential is connected directly to the upper speaking lead over contact usa. On releasing the dial plate the impulse receiving relay in the device disposed beyond the preseiector is influenced impulsively by the impulse contact mi of the dial switch. Relay A is slow to release to a certain extent so that its contacts remain in the operated position during the brief interruptions of the circuit.

All the other operations for establishing and maintaining the connection are of no interest to the invention.

When at the end of the call the receiver at the operators position is replaced the meter stepping device is started up in the exchange in the known way and transmits a number of metering impulses over the c-lead in the preselector VW corresponding to the value and duration of the established call. At the same time the relay A connected to the upper speaking lead in the fee indicator assembly GAT is caused to de-energize. Relay A opens its contact 2a and thereby opens a point in the upper speaking lead so that the operators position is completely disconnected from the fee indicator GA and the devices in the exchange. By the closing of contact 5a earth potential is applied at the fee indicator GA. Contact 6a is opened but relay H remains held in the operated position until the rst metering impulse has been transmitted over the connecting line to the fee indicator GA. For this purpose a condenser is arranged in parallel to the winding of relay H and is operated while the circuit for relay H obtains and discharges over the winding of relay I-I when this circuit is broken. Relay H is thereby made very slow-to-release so that this relay is held in the operated position until the transmission of the first metering impulse. In addition to the meter Z arranged in parallel to winding I of the seizing relay T, the metering relay ZR in the auxiliary exchange equipment is energized by the metering impulses which are transmitted in known manner by increasing the current over the c-lead. Both the meter Z and the metering relay ZR are not influenced by the normal testing and guarding current but are only operated by the increased current when metering potential is applied to the guarding lead. The contacts 'ler and 8er are opened and closed in synchronism with the incoming metering impulses. Accordingly alternating current is applied to the upper speaking lead a number of times corresponding to the number of metering impulses transmitted, an

influences the fee indicator GA in the following circuit: earth, source WQ of alternating current,

resistance Wi, contact 8er, contact 4h, condensers Kol and Ko2, windings I and II of the fee indicator GA, contact 50i and earth. The fee indicator GA is a counting device and is thus operated to register one unit charge for each impulse received; it also possesses a contact iga which is closed in synchronism with the metering impulses and each time it closes completes the following circuit for the winding of relay H over the feeding bridge: earth, contact I ga, winding of relay I-I, choke-coil DTI, the lower speaking lead, chokecoil DTS, choke-coil DM, battery and earth. Relay H accordingly remains energized during the transmission of the metering impulses and by closing its contact lh maintains the fee indicator connected to the upper speaking lead. After the transmission of the last metering impulse contact lga remains open for a prolonged period so that relay I-I is able to release and to disconnect the fee indicator by opening contact 4h.. The upper speaking lead is switched through again by the closing of contact 3h. Only now is it possible for a private branch exchange subscriber to set up a fresh call. So long as Contact 3h. is open the subscriber is completely disconnected from the public exchange devices. Accordingly he cannot for example by rapidly re-taking up the receiver and operating the dial switch and thereby applying direct earth to the speaking leads, interfere with the operations for inuencing the fee indicator. I-Ie only regains influence over the public exchange devices after the complete termination of the metering and after the upper speaking lead has been switched through at contact 3h. After the release of relay H the original condition in the fee indicator GA is re-established.

The release of the preselector takes place in the known way (which we are not at present concerned with) after the transmission of the last metering impulse.

What is claimed is:

1. In a telephone system, a substation having a line over which impulses may be received, a line relay, a switching device, an impulse receiving device, means at the substation for operating said relay, said switching device operated responsive to a first operation of said relay and said impulse receiving device rendered effective responsive to a subsequent operation of said relay, said impulse receiving device thereupon responsive to impulses received over the line and maintaining said switching device operated during the reception of said impulse thereby to prevent a further operation of said relay.

2. In a telephone system, a speaking circuit, a metering device associated with; said circuit, means operated in series with said circuit, switching means operated responsive to the operation of said last means and effective to interrupt the operating circuit for said last means, means for transmitting impulses to said metering device, and means controlled by said device to maintain said switching means operated during the reception of said impulses.

3. In a telephone system, a speaking circuit, a metering device associated with said circuit, means operated in series with said circuit, switching means operated responsive to the operation of said last means and effective both to interrupt the operating circuit for said last means and to connect said metering device to said circuit, means for transmitting impulses over said circuit to said metering device, and means controlled by said device to maintain said switching means operated during the reception of said impulses.

4. In a telephone substation having a speaking circuit, an indicating device for recording metering impulses, a supervisory device, a switching means, said supervisory device operated in series with said speaking circuit over normal contacts of said switching means and held operated in said circuit by its own contacts in shunt with said normal contacts, said switching means operated thereafter to open said normal contacts, means for subsequently operating said supervisory device to open its own contacts and for causing the transmission of metering impulses to said indicating device, said device responsive thereto to maintain said switching means operated.

5. A telephone substation as claimed in claim 4, wherein said switching means is maintained operated by impulsive energization through contacts of said indicating device.

6. In a telephone system, a line circuit, a metering device, means controlled over the line circuit for preparing an operating circuit for said device, said means reoperated to complete the operating circuit for said device and render it responsive to metering impulses, and means controlled by said device during its operation by said metering impulses for preventing any further operations of said rst means.

7. In combination with a speaking line, means for recording metering impulses transmitted thereover, supervisory means operated over said line, other means operated thereafter for preparing an operating circuit for said recording means, means for causing a subsequent operation of said supervisory means to complete an operating circuit for said recording means and for causing the transmission of metering impulses thereover, said recording means operating and simultaneously controlling said other means to prevent further operations of said supervisory means.

8. In a telephone system wherein metering impulses are transmitted to calling lines responsive to the termination of calls therefrom, the combination with a line, of a cut-off relay, a line relay responsive to the initiation of calls from said line only if said cut-off relay is in unoperated condition, means for operating said cut-off relay responsive to the operation of said line relay, and means responsive to the metering impulses transmitted to said line upon termination of each call therefrom for maintaining said cut-olf relay operated while said impulses are being received.

9. In a telephone system wherein metering impulses are transmitted to calling lines responsive to the termination of calls therefrom, the combination with a line, of a line relay operated responsive to the initiation of calls from that line, a cut-off relay operated responsive to said operation of the line relay, and means responsive to the metering impulses transmitted to said line upon termination of the call for maintaining said cut-off relay operated while the impulses are being received.

10. In a telephone system wherein the metering of calls is effected upon their termination, the combination with a line, of a meter, a line relay operated responsive to the initiation of a call from said line, a cut-off relay operated responsive to said operation of the line relay, and means controlled by said meter upon termination of said call for maintaining the cut-oil relay operated until the metering of said call has been effected.

1l; In a telephone system wherein the metering of calls is eiected upon their termination, the combination with a line, of a meter, a cut-off relay having a closed contact, a line relay operated over said contact responsive to the initiation of a call from said line, a contact of said line relay effective thereupon to shunt said contact of the cut-01T relay, said cut-off relay operated responsive to the operation of the line relay and maintained operated thereby during said call, said line relay effective to release upon termination of the call, and means controlled by said meter upon termination of the call for maintaining the cut-off relay operated until the metering of the call has been eiected. y

HERBERT Topman. 

